Aaron Zheng

Editing sketch entities in already finished part

Discussion created by Aaron Zheng on Aug 9, 2019
Latest reply on Aug 12, 2019 by John Stoltzfus

Hey everyone, this is my first discussion.

 

Anyway, I am trying to make a humanoid robot. I've finished all of my necessary designs, and have started the 3D-printing process. After experimentation I discovered some more errors whilst putting the parts together. Some of these errors were my mistake, as I am not that experienced, and some are due to slight inaccuracies. These include the length of a part being 1-2mm long or short, a hole that needs a slightly bigger diameter etcetera.

 

However, it seems that designing a part isn't that difficult, but EDITING is. Often times what I'd have is I change a dimension in a part, replace a spline, remove some unhelpful sketch relations, and many sketch errors arise, such as a failed body. This is especially so with fillets. Apparently, if you change/replace sketch entities in the first sketch, the initial sketch of the part, you risk messing up the ids of edges and vertexes, thus causing a string of unwanted errors. 

 

Here is an example:

A part which has no errors and originally looks like this, after one slight change in the first Boss-Extrude:

 

Now looks like this, with many errors and warnings.

 

This is incredibly annoying. This occurs when I replace a sketch entity in my initial boss-extrude sketch. Many times these errors force me to have to fix, or delete, if I am just too annoyed, working mates for no reason, which usually causes more problems in other assemblies that use the same part.

 

Anyway, whilst I don't have a solution to this annoying phenomenon, I do have a tip, that is, to replace sketch entities as little as possible. For my specific scenario, I wanted to reduce the height of my part. As my initial boss-extrude was mainly under-defined spline sketches, it was quite difficult to achieve this without what I did differently the second time was I simply did not replace the sketch entity. Instead, I deleted constraining dimensions and used move entities. This worked in some cases, like in the one shown above. I thought this was a much easier way. 

Surprisingly this worked without much question. My Solidworks page instead looked like this. 

It was still erroneous, but there were a lot fewer errors than the previous case.

 

All in all, with a base sketch like the image below, if you want to change critical dimensions such as the height and the width of the part, using move entities to keep relations, especially when dealing with underdefined splines, might be very helpful for you. 

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